A Review on Biological Control of Fungal Plant Pathogens Using Microbial Antagonists
ABSTRACT The objective of this study was to review the published research works on biological control of fungal plant diseases during past 50 years. Fungal plant pathogens are among the most important factors that cause serious losses to agricultural products every year. Biological control of plant diseases including fungal pathogens has been considered a viable alternative method to chemical control. In plant pathology, the term biocontrol applies to the use of microbial antagonists to suppress diseases. Throughout their lifecycle, plants and pathogens interact with a wide variety of organisms. These interactions can significantly affect plant health in various ways. Different mode of actions of biocontrol-active microorganisms in controlling fungal plant diseases include hyperparasitism, predation, antibiosis, cross protection, competition for site and nutrient and induced resistance. Successful application of biological control strategies requires more knowledge-intensive management. Various methods for application of biocontrol agents include: application directly to the infection court at a high population level to swamp the pathogen, application at one place in which biocontrol microorganisms are applied at one place (each crop year) but at lower populations which then multiply and spread to other plant parts and give protection against pathogens and one time or occasional application that maintain pathogen populations below threshold levels. Commercial use and application of biological disease control have been slow mainly due to their variable performances under different environmental conditions in the field. To overcome this problem and in order to take the biocontrol technology to the field and improve the commercialization of biocontrol, it is important to develop new formulations of biocontrol microorganisms with higher degree of stability and survival. Majority of biocontrol products are applied against seed borne and soil borne fungal pathogens, including the causal agents of seed rot, damping-off and root rot diseases. These products are mostly used as seed treatment and have been effective in protecting several major crops such as wheat, rice, corn, sugar beet and cotton against fungal pathogens. However, in some cases, biocontrol microorganisms have also been tested as spray application on foliar diseases, including powdery mildew, downy mildew, blights and leaf spots. A few post harvest fungal diseases have also been controlled by the use of antagonistic fungi and bacteria. Biocontrol microorganisms are also being used as the form of composts in some plants. Research data and observations in nurseries have shown that addition of composted organic matter to potting mixes results in suppression of soil borne diseases. A significant improvement have been made in different aspects of biological control of fungal plant diseases, but this area still need much more development and investigations to solve the existing problems. In order to have more effective biological control strategies in the future, it is critical to carry out more research studies on some less developed aspects of biocontrol, including development of novel formulations, understanding the impact of environmental factors on biocontrol agents, mass production of biocontrol microorganisms and the use of biotechnology and nano-technology in improvement of biocontrol mechanisms and strategies. Future outlooks of biocontrol of plant diseases is bright and promising and with the growing demand for biocontrol products among the growers, it is possible to use the biological control as an effective strategy to manage plant diseases, increase yield, protect the environment and biological resources and approach a sustainable agricultural system.
Article: Soil eukaryotic microorganism succession as affected by continuous cropping of peanut--pathogenic and beneficial fungi were selected.[show abstract] [hide abstract]
ABSTRACT: Peanut is an important oil crop worldwide and shows considerable adaptability but growth and yield are negatively affected by continuous cropping. Soil micro-organisms are efficient bio-indicators of soil quality and plant health and are critical to the sustainability of soil-based ecosystem function and to successful plant growth. In this study, 18S rRNA gene clone library analyses were employed to study the succession progress of soil eukaryotic micro-organisms under continuous peanut cultivation. Eight libraries were constructed for peanut over three continuous cropping cycles and its representative growth stages. Cluster analyses indicated that soil micro-eukaryotic assemblages obtained from the same peanut cropping cycle were similar, regardless of growth period. Six eukaryotic groups were found and fungi predominated in all libraries. The fungal populations showed significant dynamic change and overall diversity increased over time under continuous peanut cropping. The abundance and/or diversity of clones affiliated with Eurotiales, Hypocreales, Glomerales, Orbiliales, Mucorales and Tremellales showed an increasing trend with continuous cropping but clones affiliated with Agaricales, Cantharellales, Pezizales and Pyxidiophorales decreased in abundance and/or diversity over time. The current data, along with data from previous studies, demonstrated that the soil microbial community was affected by continuous cropping, in particular, the pathogenic and beneficial fungi that were positively selected over time, which is commonplace in agro-ecosystems. The trend towards an increase in fungal pathogens and simplification of the beneficial fungal community could be important factors contributing to the decline in peanut growth and yield over many years of continuous cropping.PLoS ONE 01/2012; 7(7):e40659. · 4.09 Impact Factor